Females may suffer from lower abdomen pains and a falling distention feeling together with waist soreness and other discomforts before and after the menstrual period or during the menstrual period, and these symptoms seriously influence the living quality. A menstrual ball is a feminine physiological product, a female usually uses a sanitary napkin for nursing when the physiological cycle arrives, but the sanitary napkin commonly has some defects in the using process. For example, the sanitary napkin is a product for external use, which cannot relieve the lower abdomen pains and the falling distention feeling which occur in the menstrual period and which may cause a leakage due to an improper placement in use or poor liquid absorbing capacity of the sanitary napkin. Moreover, when the female walks or does some exercises, friction is generated between side walls of the sanitary napkin and both legs, which may makes the user uncomfortable. Since the sanitary napkin is a product for external use and adsorbing liquid, the female cannot take part in underwater activities, e.g., swimming and the like, when she is using a sanitary napkin. In order to solve various problems above, currently, reusable menstrual cups are commercially available, the existing menstrual cups are all of a fixed shape structure, a closed effect is generated after the menstrual cup is placed into the vagina of a female, and during the menstrual period, a menstrual cup body structure is used for containing menstrual blood. However, when the menstrual blood is discharged out of the body, air in the menstrual cup cannot be exhausted, thus the female will have an abdominal distention feeling when using the menstrual cup.